System and method for heating biological tissue via RF energy

Abstract

A system 30 and method(s) 100 for thermal treatment of a selected target within a subject is disclosed. System 30 includes RF source 10 , phase shifter 14 , impedance matching network 11 and resonator 13 . Stationary water molecules 1 , such as those in fat cells, are heated. The invention is useful in selective heating of cellulite bodies as a means of treating cellulite.

What is claimed: 
     
       1. An improved system for thermal treatment of a selected target within a subject, the system comprising:
 (a) an electromagnetic (EM) energy source capable of producing an output EM power signal directed to an applicator contactable with a surface of a biological tissue belonging to the subject, said applicator capable of delivering a desired amount of energy to a predetermined energy dissipation zone beneath said surface of said biological tissue, the selected target positioned within said predetermined energy dissipation zone; 
 (b) a phase shifter, said phase shifter capable of shifting a phase of EM waves of said output EM signal so that energy therefrom is concentrated primarily in said predetermined energy dissipation zone, which lies at a desired depth beneath said surface of said biological tissue; 
 (c) an electromagnetic (EM) resonator, said EM resonator capable of cyclically accumulating and releasing said desired amount of energy, said EM resonator further capable of concentrating said desired amount of energy so that a significant portion thereof is concentrated in said predetermined energy dissipation zone; and 
 (d) said applicator capable of conveying said output EM power signal from said EM energy source through said surface of said biological tissue to said predetermined energy dissipation zone after said output has been processed by said phase shifter and said resonator; 
 wherein the absence of a ground electrode permits free propagation of said waves of said output EM power signal in said energy dissipation zone. 
 
     
     
       2. The system of  claim 1 , further comprising a pulse width modulation controller, said pulse width modulation controller capable of causing said EM energy source to deliver said output signal in pulses of a predetermined duration and amplitude with a desired frequency. 
     
     
       3. The system of  claim 1  wherein said resonator is connected to said applicator. 
     
     
       4. The system of  claim 1  wherein said resonator is located within said applicator. 
     
     
       5. The system of  claim 1  wherein the EM energy source is a radio frequency (RF) energy source and the EM power signal is an RF power signal. 
     
     
       6. The system of  claim 1  wherein
 the system further comprises an impedance matching network (IMN) configured to reduce reflection of output RF power from a surface of biological tissue to the electromagnetic (EM) energy source. 
 
     
     
       7. The system of  claim 6 , further comprising a feeding cable, said feeding cable connecting said applicator and said EM resonator with said IMN. 
     
     
       8. The system of  claim 7 , wherein said feeding cable has a resonance length defined by n*λ/2 length, where λ is a wavelength of EM-energy in the cable material and n is a whole number. 
     
     
       9. The system of  claim 6 , wherein the system is configured so that at least one of a first condition, a second condition and a third condition is true, and the first, second and third conditions are defined as follows:
 i) according to said first condition, said IMN includes a fixed structure characterized by a shape selected from the group consisting of L shaped, T shaped and Π-shaped structure; 
 ii) according to said second condition, said IMN includes a broadband impedance transformer; and 
 iii) according to said third condition, said IMN is variable. 
 
     
     
       10. The system of  claim 1 , further comprising a dielectric barrier positionable between said applicator and said surface of said biological tissue; said dielectric barrier preventing transmission of a conductive current, wherein the system is configured so that at least one of a first condition and a second condition is true and the first and second conditions are defined as follows:
 i) according to the first condition, said dielectric barrier is supplied as a dielectric coating on said applicator; and 
 ii) according to the second condition, said applicator is constructed primarily of aluminum and said dielectric barrier is supplied as an alumina coating. 
 
     
     
       11. The system of  claim 1 , wherein said applicator is movable on said surface of said biological tissue as a means of altering a location of said energy dissipation zone. 
     
     
       12. The system of  claim 1 , wherein the system is configured so that at least one of a first condition, a second condition and a third condition is true, and the first, second and third conditions are defined as follows:
 i) according to said first condition, said phase shifter includes a trombone type; 
 ii) according to said second condition, said phase shifter is at least partially constructed of coaxial cable; and 
 iii) according to said third condition, a phase shift provided by said phase shifter is variable. 
 
     
     
       13. The system of  claim 1 , said EM energy source is configured to deliver coupled energy. 
     
     
       14. The system of  claim 1 , wherein said system is configured such that said energy delivered to said predetermined energy dissipation zone is coupled in continuous or pulsing mode. 
     
     
       15. The system of  claim 1 , wherein said EM-energy is characterized by a resonance frequency which matches a known natural resonance frequency of the selected target. 
     
     
       16. The system of  claim 1  wherein the system is configured to heat said volume of said biological tissue beneath said surface so that said volume of said biological tissue is maintained at a lower temperature than said predetermined energy dissipation zone without a cooling device. 
     
     
       17. The system of  claim 1 , further comprising at least one additional component selected from the group consisting of a laser beam, an ultrasonic transducer, a UV light source, a plasma treatment device and a flash lamp. 
     
     
       18. An improved method for thermal treatment of a selected target within a subject, the method comprising:
 (a) providing an output EM power signal directed to an applicator contactable with a surface of a biological tissue belonging to the subject, 
 (b) employing a phase shifter to shift a phase of EM waves in said output EM power signal so that energy therefrom is concentrated primarily in a predetermined energy dissipation zone which lies at a desired depth beneath said surface of said biological tissue, wherein the selected target is positioned within said predetermined energy dissipation zone; 
 (c) cyclically accumulating in an EM resonator and releasing therefrom, a desired amount of energy, 
 (d) concentrating said desired amount of energy in said EM resonator so that a significant portion thereof is concentrated in said predetermined energy dissipation zone upon release therefrom; and 
 (f) conveying said output signal of EM energy through said surface of said biological tissue to said predetermined energy dissipation zone after said output has been processed by said phase shifter, and said resonator wherein the absence of a ground electrode permits free propagation of said waves in said output signal in said energy dissipation zone. 
 
     
     
       19. The method of  claim 18 , wherein said providing of said EM output signal includes provision of said output signal in pulses of a predetermined duration and amplitude with a desired frequency. 
     
     
       20. The method of  claim 18  wherein said resonator is connected to said applicator. 
     
     
       21. The method of  claim 18  wherein said resonator is located within said applicator. 
     
     
       22. The method of  claim 18  wherein the EM energy source is a radio frequency (RF) energy source and the EM power signal is an RF power signal. 
     
     
       23. The method of  claim 18  wherein:
 (i) the method further comprises the step of converting the impedance of said biological tissue belonging to the subject from a nominal value to a corrected value by means of an impedance matching network (IMN) in order to reduce reflection of EM power from a surface of the biological tissue; and 
 (ii) said output EM power signal that is conveyed through said surface of said biological tissue to said predetermined energy dissipation zone is processed by said IMN. 
 
     
     
       24. The method of  claim 23 , further comprising employing a feeding cable to connect said applicator and said resonator with said IMN. 
     
     
       25. The method of  claim 24 , wherein said feeding cable has a resonance length defined by n*λ/2 length, where λ is a wavelength of EM-energy in the cable material and n is whole number. 
     
     
       26. The method of  claim 23 , wherein the method is carried out so that at least one of a first condition, a second condition and a third condition is true, and the first, second and third conditions are defined as follows:
 i) according to said first condition, said IMN includes a fixed structure characterized by a shape selected from the group consisting of L shaped, T shaped and Π-shaped structure; 
 ii) according to said second condition, said IMN includes a broadband impedance transformer; and 
 iii) according to said third condition, said IMN is variable. 
 
     
     
       27. The method of  claim 18 , further comprising interposing a dielectric barrier between said applicator and said surface of said biological tissue; said dielectric barrier preventing transmission of a conductive current. 
     
     
       28. The method of  claim 27 , wherein the method is carried out so that at least one of a first condition and a second condition is true, and the first, and second conditions are defined as follows:
 i) according to the first condition, said dielectric barrier is supplied as a dielectric coating on said applicator; and 
 ii) according to the second condition, said applicator is constructed primarily of aluminum and said dielectric barrier is supplied as an alumina coating. 
 
     
     
       29. The method of  claim 18 , further comprising moving said applicator with respect to said surface of said biological tissue as a means of altering a location of said energy dissipation zone. 
     
     
       30. The method of  claim 18 , wherein the method is carried out so that at least one of a first condition, a second condition and a third condition is true, and the first, second and third conditions are defined as follows:
 i) according to said first condition, said phase shifter includes a trombone type; 
 ii) according to said second condition, said phase shifter is at least partially constructed of coaxial cable; and 
 iii) according to said third condition, a phase shift provided by said phase shifter is variable. 
 
     
     
       31. The method of  claim 18 , wherein said provided output signal of EM energy is indicative of coupled energy. 
     
     
       32. The method of  claim 18 , wherein said energy delivered to said predetermined energy dissipation zone is coupled in continuous or pulsing mode. 
     
     
       33. The method of  claim 18 , wherein said desired amount of energy released by said EM resonator is characterized by a resonance frequency that matches a known resonance frequency of the selected target. 
     
     
       34. The method of  claim 18 , wherein (a) through (e) are performed in the order listed. 
     
     
       35. The method of  claim 18  wherein:
 i) said predetermined energy dissipation zone includes at least one cellulite body; 
 ii) the method is carried out so that said at least one cellulite body is heated to 
 a greater degree than a tissue adjacent thereto. 
 
     
     
       36. The method of  claim 18  wherein the method is carried out to heat a volume of said biological tissue beneath said surface so that said surface of said biological tissue is maintained at a lower temperature than said predetermined energy dissipation zone without a cooling device. 
     
     
       37. The method of  claim 18  wherein said applicator is made from at least one metal selected from the group consisting of aluminum, silver, gold, copper and alloys thereof.